ASoC: qcom: sm8250: Fix array out of bounds access

Static analysis Coverity had detected a potential array out-of-bounds
write issue due to the fact that MAX AFE port Id was set to 16 instead
of using AFE_PORT_MAX macro.

Fix this by properly using AFE_PORT_MAX macro.

Fixes: aa2e2785 ("ASoC: qcom: sm8250: add sound card qrb5165-rb5 support")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>